#include <cstdio>

void changeData(int *x)
{
	*x = 20;
}

void changeData2(int &x)
{
	x = 20;
}

int main()
{
	int a = 50;
	changeData2(a);
	printf("a = %d\n", a);
	
	int c = 30;
	int &d = c;
	d = 1000;
	printf("c = %d", c);
	return 0;
} 
